1. Technical Field
The present invention relates to a method for producing a semiconductor device and to a semiconductor device.
2. Related Art
Conventionally, in silicon semiconductor integrated circuits (hereafter referred to as LSI), aluminum (Al) or Al alloy has been used as an electrically conductive material. Then, in accordance with a progress in miniaturization of the LSI, copper (Cu) has come to be used as an electrically conductive material in order to achieve reduction of interconnect resistance and higher reliability of the interconnect. Since Cu is easily diffused into a silicon oxide layer, an electrically conductive barrier metal layer for preventing diffusion of Cu is generally used on the side surface and on the bottom surface of the Cu interconnect, and an insulative barrier layer is used on the top surface of the Cu interconnect.
In accordance with the miniaturization of the LSI in recent years, miniaturization of the interconnect dimension is also in progress, thereby raising a problem of increase in the capacitance between the interconnects. For this reason, introduction of a porous low dielectric constant layer is promoted as an insulating interlayer. This is because, by reducing the dielectric constant in the insulating interlayers of a multilayer interconnect in a semiconductor device, increase in the signal transmission speed and reduction of the driving power can be achieved.
For reduction of the dielectric constant of the insulating interlayer, an attempt has been made to increase the porosity of the insulating interlayer by introducing a porogen into the insulating interlayer and eliminating the porogen or to introduce hydrocarbon into the insulating interlayer. A low dielectric constant layer is, for example, a HSQ (Hydrogen Silsesquioxane) layer, a CDO (Carbon doped oxide) layer, an organic layer, or the like. These low dielectric constant layers are formed by the rotation application method, the vapor growth method, or the like.
In recent years, a film deposition method for forming an insulating interlayer having a low specific dielectric constant by using a plurality of source materials has been reported.
International Application No. 2007/032261 discloses a method for forming a porous insulating film by the plasma CVD (Chemical Vapor Deposition) method wherein a mixed gas of a cyclosiloxane material and a straight-chain material containing a part of the chemical structure constituting a organic cyclosiloxane material is used.
International Application No. 2008/010591 discloses a method for mixing a three-membered-ring organic siloxane source material gas and a four-membered-ring organic siloxane source material gas in a reaction chamber and obtaining an insulating film having a high strength and a high close adhesion strength by the plasma CVD or the plasma polymerization method.
Japanese Laid-open patent publication No. 2003/045870 discloses a method for obtaining a dielectric substance having a low k value by allowing a silsesquioxane compound to react with a coupling agent.
Japanese Laid-open patent publication Nos. 2006/005206 and 2008/263022 disclose a method for forming a low dielectric constant layer by using compounds having specific structures, respectively.